1. Field of the Invention
The present invention relates to the field of robotics and, more particularly, to a hand-held, compact device to be used as a portable dextrous master in a telemanipulation robotic system.
2. Description of the Prior Art
Present telemanipulation techniques include the use of mechanical masters, open-loop servomasters, and to a lesser extent, closed-loop servomasters Direct mechanical telemanipulation is often the simplest method, but cannot be used in applications where the slave is not in the immediate vicinity of the master. Closed-loop telemanipulation eliminates the proximity requirement but may necessitate the need to have two nearly identical devices to act as master and slave. This duplication of resources is often prohibitive in terms of cost and payload weight
Efforts have been made to eliminate the duplicate master by replacing it with force feedback joy sticks, sensorized spheres, pistol grips and the like. Although such devices have served the purpose, they have not proved entirely satisfactory under all conditions of service because these devices are less "natural" to use by an operator since direct similitude does not exist between human hand and robot finger motions. Examples of manual controllers using levers, grippers, handles and like devices, with many having force feedback, may be found in the following U.S. Pat. Nos.: 4,795,296; 3,995,831; 4,604,016; 3,618,786; 3,637,092; and 3,771,037.
Those concerned with the development of telemanipulation devices have recognized the disadvantages of such prior art controllers and the need for a dextrous master controller that uses an operator's hand to replace the classical manipulator arm, the conventional keypad contact, the joy stick or handle, or other similar structure. Use of the human hand is a natural form of control and is applicable for use with both non-dextrous and dextrous slave devices. Further, because the human hand is used as master, duplication of most hardware is not required; and weight, inertia and friction can be reduced. Under most conditions, significant improvements in the time necessary to complete a task can be realized when using the human hand as the master. For example, it has been estimated that an improvement on the order of ten can be expected on the time efficiency when a dextrous master is used in place of a conventional keypad control.
While open-loop dextrous masters create more natural control environments, they lack the ability to bring force feedback to the operator's hand, which in turn limits the utility of the slave device. On the other hand, a dextrous master with force feedback, using much of the human hand as master in a closed-loop teleoperation environment, will allow the efficient execution of complex tasks such as assembly and repair involving the telemanipulation of small, intricately shaped parts. Examples of robotic masters with force feedback and wherein much of the human hand is used as the master may be found in the following U.S. Pat. Nos.: 3,449,008; 3,171,549; and 4,302,139.
Again, these examples demonstrate various prior art attempts at obtaining a controller that would be more "natural" to the operator. Although there has been a long recognized need for a "natural" dextrous master that more closely simulates the motions of the fingers of a dextrous slave, no practical system for doing so has yet been devised. Ideally, such a system should have the capability of being held in a natural position in the operator's hand; would be operated by the operator performing a natural movement; would be relatively light weight; would include a force feedback mechanism that affects the operator's hand in a manner that corresponds directly to the forces generated at the slave; would be compact, portable and simple in construction; and would be dependable in operation. The present invention fulfills this need.